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Jane F. Hislop, Cathy Bulley, Tom H. Mercer, and John J. Reilly

The objectives of this study were to explore whether triaxial is more accurate than uniaxial accelerometry and whether shorter sampling periods (epochs) are more accurate than longer epochs. Physical activity data from uniaxial and triaxial (RT3) devices were collected in 1-s epochs from 31 preschool children (15 males, 16 females, 4.4 ± 0.8 yrs) who were videoed while they engaged in 1-hr of free-play. Video data were coded using the Children’s Activity Rating Scale (CARS). A significant difference (p < .001) in the number of minutes classified as moderate to vigorous physical activity (MVPA) was found between the RT3 and the CARS (p < .002) using the cut point of relaxed walk. No significant difference was found between the GT1M and the CARS or between the RT3 and the CARS using the cut point for light jog. Shorter epochs resulted in significantly greater overestimation of MVPA, with the bias increasing from 0.7 mins at 15-s to 3.2 mins at 60-s epochs for the GT1M and 0 mins to 1.7 mins for the RT3. Results suggest that there was no advantage of a triaxial accelerometer over a uniaxial model. Shorter epochs result in significantly higher number of minutes of MVPA with smaller bias relative to direct observation.

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Louise A. Kelly, John J. Reilly, Diane M. Jackson, Colette Montgomery, Stanley Grant, and James Y. Paton

Tracking of total physical activity (PA), moderate to vigorous activity (MVPA), and sedentary behavior was assessed in 42 young children (mean age at baseline 3.8 years) over a 2-year period using the Actigraph accelerometer. Tracking was analyzed using Spearman rank correlations, percentage agreements, and kappa statistics. Spearman rank correlations were r = .35 (p = .002) for total PA, r = .37 (p = .002) for MVPA, and r = .35 (p = .002) for sedentary behavior. Percentage agreements for PA, MVPA, and sedentary behavior were 38, 41, and 26 respectively. Kappa statistics for PA, MVPA, and sedentary behavior ranged from poor to fair. Results suggest low levels of tracking of total physical activity, MVPA, and sedentary behavior in young Scottish children over a 2-year period.

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Robert M. Ojiambo, Chris Easton, Jose A. Casajús, Kenn Konstabel, John J. Reilly, and Yannis Pitsiladis

Background:

Urbanization affects lifestyles in the developing world but no studies have assessed the impact on objectively measured physical activity in children and adolescents from sub-Saharan Africa.

Purpose:

To compare objectively measured habitual physical activity, sedentary time, and indices of adiposity in adolescents from rural and urban areas of Kenya.

Methods:

Physical activity and sedentary time were assessed by accelerometry for 5 consecutive days in 97 (50 female and 47 male) rural and 103 (52 female and 51 male) urban adolescents (mean age 13 ± 1 years). Body Mass Index (BMI) and BMI z-scores were used to assess adiposity.

Results:

Rural males spent more time in moderate-to-vigorous intensity physical activity (MVPA) compared with urban males (68 ± 22 vs. 50 ± 17 min, respectively; P < .001). Similarly, Rural females spent more time in MVPA compared with urban females (62 ± 20 vs. 37 ± 20 min, respectively; P < .001). Furthermore, there were significant differences in daily sedentary time between rural and urban subjects. Residence (rural vs. urban) significantly (P < .001) influenced BMI z-score (R 2 = .46).

Conclusion:

Rural Kenyan adolescents are significantly more physically active (and less sedentary) and have lower indices of adiposity compared with urban adolescents and this is a likely refection of the impact of urbanization on lifestyle in Kenya.

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Louise A. Kelly, John J. Reilly, Sheila C. Fairweather, Sarah Barrie, Stanley Grant, and James Y Paton

The primary aim of this study was to test the validity of two accelerometers, CSA/MTI WAM-7164 and Actiwatch®, against direct observation of physical activity using the Children’s Physical Activity Form (CPAF). CSA/MTI WAM-7164 and Actiwatch accelerometers simultaneously measured activity during structured-play classes in 3- to 4-year olds. Accelerometry output was synchronized to CPAF assessments of physical activity in 78 children. Rank order correlations between accelerometry and direct observation evaluated the ability of the accelerometers to assess total physical activity. Within-child minute-to-minute correlations were calculated between accelerometry output and direct observation. For total physical activity, CSA/MTI output was significantly correlated with CPAF (r = .72, p < .001), but output from the Actiwatch was not (r = .16, p > .05).

Open access

Chiaki Tanaka, Shigeho Tanaka, Shigeru Inoue, Motohiko Miyachi, Koya Suzuki, and John J. Reilly

Background:

The Report Card on Physical Activity for Children and Youth aims to consolidate existing evidence, encourage greater evidence-informed physical activity, and improve surveillance of physical activity.

Methods:

The Japan report card followed the methodology of the Canadian and Scottish report cards, but was adapted to reflect the Japanese context. Nationally representative data were used to score each of the respective indicators.

Results:

The 2016 Japan Report Card on Physical Activity for Children and Youth consists of Health Behaviors and Outcomes (7 indicators), and Influences on Health Behaviors (4 indicators). Three Health Behaviors and Outcomes received C grades (Participation in Sport; Sedentary Behavior; Recreational Screen Time; Physical Fitness), while 2 indicators could not be graded (Overall Physical Activity, and Active Play). The indicators Active Transportation (B) and Weight Status were favorable (A). In the Influences domain, Family Influence and Community and the Built Environment were graded as D, while School and Government Strategies and Investments were favorable (B).

Conclusions:

The Japan report card illustrated some favorable health behaviors, health outcomes, and influences. There is a need for more evidence especially on overall physical activity levels, active play, and community and the built environment.

Open access

Mohamed G. Al-Kuwari, Izzeldin A. Ibrahim, Eiman M. Al Hammadi, and John J. Reilly

Background:

The first Qatar Active Healthy Kids (QAHK) Report Card was developed in 2015–2016. It is a synthesis of the available evidence on physical activity in children and youth in the state of Qatar—an assessment of the state of the nation. The report card is important for future physical activity advocacy, policy, and program development.

Methods:

The QAHK Report Card was inspired by the Active Healthy Kids Scotland 2013 Report Card. The methodology used in Scotland’s report card was adapted for Qatar. A Working Group identified indicators for physical activity and related health behaviors, and evaluated the available data on these indicators. The card grades were determined by the percentage of children meeting guidelines or recommendations.

Results:

The 2016 QAHK Report Card consisted of 9 indicators: 6 Physical Activity and Health Behaviors and Outcomes, and 3 Settings and Influences on these health behaviors and outcomes. The indicator National Policy, Strategy, and Investment was assigned the highest grade (B). Four indicators were assigned D grades: Sedentary Behavior, Dietary Habits, Organized Sports Participation, and Family and Peer Influence. Physical Activity and Obesity were both graded F. Two indicators could not be graded due to insufficient data and/or absence of a recommendation: Active and Outdoor Play, and Community and School Influence.

Conclusions:

The QAHK Report Card identified weaknesses and gaps in the evidence on physical activity and health in children and youth in Qatar. The quality of evidence was poor for some indicators, with some data collection methods of limited validity and reliability, or only available for a limited age range, so the grades are best estimates of the current situation in Qatar. Future surveys and research using objective physical activity measures will support the development of a second QAHK Report Card by 2018.

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Sheila C. Fairweather, John J. Reilly, Stanley Grant, Arthur Whittaker, and James Y. Paton

The primary aim of this study was to assess the ability of the CSA accelerometer to measure physical activity in preschool children. A secondary aim was to examine inter-instrument differences and the effect of accelerometer placement on output. Eleven subjects (mean age = 4.0 years, SD = 0.4) wore the CSA-7164 for a 45-min preschool exercise class. They were observed throughout the class, and their engagement in activity was quantified using the Children’s Physical Activity Form (CPAF). The effect of accelerometer positioning (left vs. right hip) was assessed in 10 subjects over 2 days. CSA output during the class was highly correlated with the CPAF score (r = 0.87, p < .001), and rank order correlations between the 2 methods were also highly significant (r = 0.79, p < .01). Differences in CSA output between left and right hip reached statistical significance (paired t, p < .05), but these differences were small and probably of limited biological significance. The CSA appears to be an appropriate tool for assessment of physical activity in preschool children, but further studies on stability of activity as measured by CSA, as well as its validity, are urged.

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Anne Martin, Paul Kelly, Jessica Boyle, Fenella Corlett, and John J. Reilly

Purpose:

This study estimated the contribution of walking to/from school to objectively measured daily moderate-vigorous intensity physical activity (MVPA) in individuals and populations.

Methods:

MEDLINE, PsycINFO and SPORTDiscus were systematically searched up to February 2015. Two reviewers independently screened titles/abstracts/full-text articles, and assessed study quality.

Results:

Of 2430 records, 129 were eligible for full-text screening. Twelve studies met the inclusion criteria of reporting objectively obtained measures of MVPA (total and while walking to/from school) in children and adolescents. The weighted mean MVPA accumulated in walking to and from school was 17 min/day in primary school pupils (9 samples, n = 3422) and 13 min/day in high school pupils (4 samples, n = 2600). Pooled analysis suggested that walking to and from school contributed 23% and 36% of MVPA on schooldays in primary school age children and high school pupils, respectively. All included studies were of high methodological quality.

Conclusions:

Walking to and from school makes a meaningful contribution to individual schoolday MVPA for active commuters in western countries. Since schooldays represent only around half of all days, and prevalence of walking to school is low in many countries, the contribution of walking to school to population MVPA is probably low.

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Chiaki Tanaka, Xanne Janssen, Mark Pearce, Kathryn Parkinson, Laura Basterfield, Ashley Adamson, and John J. Reilly

Background: Previous studies have reported on the associations between obesity and sedentary behavior (SB) or physical activity (PA) in children. This study examined longitudinal and bidirectional associations between adiposity and SB and PA in children. Methods: Participants were 356 children in England. PA was measured at 7 and 9 years of age using accelerometry. Outcome and exposures were time in SB and PAs and concurrent body mass index z score and fat index (FI). Results: Adiposity at baseline was positively associated with changes in SB (β = 0.975 for FI) and negatively associated with changes in moderate to vigorous PA (β = −0.285 for body mass index z score, β = −0.607 for FI), vigorous PA (β = −0.095 for FI), and total PA (β = −48.675 for FI), but not vice versa. The changes in SB, moderate to vigorous PA, and total PA for children with overweight/obesity were significantly more adverse than those for children with healthy weight. Conclusions: A high body mass index z score or high body fatness at baseline was associated with lower moderate to vigorous PA and vigorous PA after 2 years, but not vice versa, which suggests that in this cohort adiposity influenced PA and SB, but the associations between adiposity and SB or PA were not bidirectional.

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Kieran P. Dowd, Helen Purtill, Deirdre. M. Harrington, Jane F. Hislop, John J. Reilly, and Alan E. Donnelly

Objectives:

This study aims to determine the minimum number of days of monitoring required to reliably predict sitting/lying time, standing time, light intensity physical activity (LIPA), moderate-to-vigorous intensity physical activity (MVPA) and steps in adolescent females.

Method:

195 adolescent females (mean age = 15.7 years; SD = 0.9) participated in the study. Participants wore the activPAL activity monitor for a seven day protocol. The amount of time spent sitting/lying, standing, in LIPA and in MVPA and the number of steps per day were quantified. Spearman-Brown Prophecy formulae were used to predict the number of days of data required to achieve an intraclass correlation coefficient of both 0.7 and 0.8.

Results:

For the percentage of the waking day spent sitting/lying, standing, in LIPA and in MVPA, a minimum of 9 days of accelerometer recording is required to achieve a reliability of ≥ 0.7, while a minimum of 15 days is required to achieve a reliability of ≥ 0.8. For steps, a minimum of 12 days of recording is required to achieve a reliability of ≥ 0.7, with 21 days to achieve a reliability of ≥ 0.8.

Conclusion:

Future research in adolescent females should collect a minimum of 9 days of accelerometer data to reliably estimate sitting/lying time, standing time, LIPA and MVPA, while 12 days is required to reliably estimate steps.